1. Field of the Invention
The present invention relates to a medical apparatus known as a laryngoscope that is used to facilitate endotracheal intubation of a patient. Intubating a patient provides an airway when the patient requires assistance in breathing. The laryngoscope may also be used to assist in the examination of the larynx and surrounding area.
2. Description of the Prior Art
Laryngoscopes are well-known in the art and have been used to assist in intubating patients during emergency situations to provide resuscitation or mechanical ventilation. Laryngoscopes are also used in a more controlled environment, for example in preparation for surgery. Intubation requires the insertion of a flexible tube through the oral cavity, the oropharynx, and into the trachea. It is essential that the practitioner inserting the tube have a clear view of the epiglottis and the vocal chords to enable the practitioner to guide the tube into the trachea without injury to the patient.
A standard laryngoscope comprises a stainless steel handle and a laryngoscope blade. The handle houses batteries as a power source for a light that is attached to the blade. One end of the laryngoscope blade is releasably secured at a generally right angle to the handle. The attachment point closes the electrical connection between the battery and the light. The practitioner inserts the blade into the throat through the oral opening with the aid of the light which is attached proximal to the other end of the blade.
There are many factors that come into play when someone is being intubated, but the most important factor is an unobstructed view of the patient's vocal chords which lie at the entrance to the trachea where the tube is to be inserted. The two most common laryngoscope blades available are the Miller blade, which is disclosed in U.S. Pat. No. 5,065,738 issued to Van Dam, and the Macintosh blade, which is disclosed in U.S. Pat. No. 2,354,471 issued to R. R. Macintosh.
The Miller blade is a straight blade that has a round tubular shape and a small diameter. The Miller blade has a longitudinal axis which generally coincides with the line of sight used during intubation. The blade is concave in relation to the longitudinal axis and the exterior surface of the concave portion of the blade contacts the tongue of the patient during intubation. As the blade is concave, the patient's tongue easily moves around the blade obstructing the view of the oropharynx. When the tongue is free to move, the patient also uses his tongue in an attempt to eject the blade from his mouth making intubation difficult. In addition, the maximum distance between the flange 38 of the Miller blade and its concave upper surface 42, vertical spacing, is small, such that when a patient bites on the blade, the blade cannot keep the mouth open wide enough for the practitioner to easily see the vocal chords.
The Macintosh blade has a longitudinal axis that is curved throughout most of its length. Viewing the vocal chord area through a curved blade is like trying to look around a bend in the road when driving a car. The Macintosh blade has a wide and flat cross-section, unlike the Miller blade and controls the tongue better but the patient can still move his tongue around the blade and obstruct the practitioner's view of the chords. When a patient's epiglottis is anterior the neck, closer to the front of the neck, it requires extreme lift force be applied to the tongue and surrounding tissues to move the epiglottis away from the line of sight and thus overcome the loss of sight attributed to the curve of the blade.
Notwithstanding the existence of such prior art blades, it remains clear that there is a need for blades that can better control the patient's tongue, provide a clearer view of the oropharynx and the vocal chords and cause less damage to the surrounding tissue of the patient.